1. Field of the Invention
The present invention relates to a driver's airbag module assembly structure, and more particularly, to a driver's airbag module assembly structure enabling easy assembly of an airbag module installed in a steering wheel.
2. Description of the Prior Art
Generally, an airbag system for an automobile is a safety device for reducing injury due to impact in a collision by instantly inflating an airbag installed in a steering wheel or a glove box between a driver and the steering wheel or between a passenger and the glove box. The airbag system works independently from a seat belt.
The airbag system for driver/passenger has an inflator for generating gas by igniting an exploder. The gas generated by the inflator expands to deploy the airbag toward the driver sitting in the driver's seat.
In addition, the airbag system includes a mounting plate fixed to a cover member provided on the steering wheel by a bolt, etc., an airbag module having a horn plate, and so on, installed on the mounting plate, an impact sensor for detecting an impact signal upon collision, and an electronic control module for igniting the exploder of the inflator in response to the impact signal.
The airbag of the driver's airbag module is covered with the cover member separated from the steering wheel when the airbag is expanded. The inflator of the driver's airbag module contains a gas generating agent for expanding gas generated by igniting the exploder and supplying the expanding gas into the airbag.
However, in the conventional art, since the mounting plate and the cover member are assembled by fastening the bolt, the assembly process is complicated and the number of parts is increased, thereby increasing manufacturing cost and weight.
FIG. 1A is an exploded perspective view of an airbag module assembly structure.
As shown in FIG. 1A, the airbag module includes a cover member 30a supported by ribs 22a formed at a rear surface of an airbag module cover 20a, a mounting plate 40a engaged with the cover member 30a, fastening parts 50a formed on the mounting plate 40a, and fastening support parts 60a formed on the cover member 30a. 
Each of the fastening parts 50a includes a fastening hole 52a formed at the cover member 30a, and a fastening piece 54a projecting from a side surface of the mounting plate 40a to pass through the fastening hole 52a, and bent at its tip away from the fastening hole 52a. 
In addition, each of the fastening support parts 60a includes a coupling hole 62a formed at the cover member 30a, and a fastening support piece 64a projecting from the side surface of the mounting plate 40a to be hooked by the fastening hole 62a. The fastening support part 60a is formed adjacent to the fastening part 50a. 
Further, the coupling hole 62a has a fastening aperture (not shown) through which the fastening support piece 64a passes, and a support threshold (not shown) formed at a predetermined space vertically punched from the fastening aperture. Here, the coupling hole 62a further includes a support aperture formed under the support threshold and in communication with the fastening aperture.
FIG. 1B is an exploded perspective view of another airbag module assembly structure different from that of FIG. 1A.
As shown in FIG. 1B, the airbag module assembly structure includes a mounting plate 20b having coupling projections 22b, and a cover member 30b having coupling holes 32b, the coupling projections 22b and the coupling holes 32b being engaged with each other.
Each of the coupling projections 22b includes a fastening piece (not shown) projecting from a side surface of the mounting plate 20b with a uniform thickness and bent at its tip away from the engagement, and a support piece (not shown) having a width smaller than the fastening piece and extending from an upper surface of the fastening piece to an outer surface of the mounting plate.
In addition, each of the coupling holes 32b includes a fastening aperture (not shown) through which the tip of the fastening piece passes to be inserted, a guide aperture (not shown) vertically punched from the fastening aperture to a predetermined distance to guide vertical movement of the support piece, and a support threshold (not shown) naturally formed by forming the fastening aperture and the guide aperture.
The coupling hole 32b further includes a support aperture horizontally elongated from a position vertically adjacent to the fastening aperture and through which the guide aperture passes.
FIG. 1C is an exploded perspective view of yet another airbag module assembly structure different from those of FIGS. 1A and 1B.
As shown in FIG. 1C, the airbag module assembly structure includes a mounting plate 40c, a cover member 30c formed at a rear surface of an airbag module cover 20c, and coupling projections 42c and coupling holes 32c coupled with each other.
Each of the coupling projections 42c includes a body projecting from an outer surface of the mounting plate 40c and having an upper width larger than a lower width, and a tip bent away from a coupling direction of the body.
In addition, the coupling hole 32c includes a fastening aperture formed at the cover member 30c and through which an upper part of the body passes.
However, since all of the conventional art described above requires strong external force for coupling the cover member and the mounting plate, assembly is a time consuming operation, therefore lowering productivity.
Further, FIG. 1D illustrates a conventional driver's airbag module assembly structure.
As shown in FIG. 1D, the conventional driver's airbag module assembly structure includes an insert 2 formed of a flat plate, and a base plate 25 detachably installed at the insert 2. The insert 2 has bushings 28 projecting upward from the insert 2, and locking springs 29 resiliently installed at the bushings 28.
In addition, the base plate 25 has snap pins 26 projecting from a lower surface thereof corresponding to the bushings 28 and fixing an inflator 21 at a center thereof. The snap pins 26 have fastening grooves 26a allowing detachable installation into the locking springs 29.
In the conventional airbag module assembly structure, the snap pins 26 of the base plate 25 are inserted into the bushings 28 of the insert 2, and the locking springs 29 are hooked by the fastening grooves 26a, thereby securely fixing the base plate 25.
Since the conventional airbag module assembly structure is fastened by the bushings, the locking springs, and the snap pins, it is possible to reduce the number of parts required for mounting the airbag module, thereby improving assembly performance and reducing manufacturing cost. In addition, since the base plate should be strongly pressed and assembled into the insert, its assembly operation is also difficult.